Lapping apparatus



0'. A. WALLACE All March 26, 1940.

LAPPING APPARATUS Filed Nov. 8, 1937 .L NM 41 2- M. ATTORNEY-'5.

Patented Mar. 26, 1940 LAPPING APPARATUS David A. Wallace and Edward C. Lee, Detroit,

Mich.,

assignors to Chrysler Corporation,

Highland Park, Micln, a corporation of Delaware Application November 8, 1937, Serial No. 173.292

3 Claims.

This invention relates to improved apparatusfor lapping internal cylindrical surfaces.

More particularly, the invention pertains to improvements in the apparatus for lapping internal surfaces of internal combustion engine cylinders, bearings and the like.

One of the main objects of the invention is to provide lapping apparatus by which the lapping elements-may be expanded and urged by a predetermined lapping pressure toward and contracted away from the work during normal operation of the lapping apparatus.

Another object of the invention resides in the provision of an apparatus of this character by which this expanding and contracting movement of the lapping elements is imparted by a nonrotating piston through a novel connection to the rotating and reciprocating elements of lapping apparatus in response to the admittance of fluid pressure, preferably air pressure, to act on the piston.

A further object of the invention resides in the provision of apparatus of this character by which the lapping tool may be reciprocated at a speed of substantially vibratory order while at the same time reciprocated at a slower speed and throughout a longer course and rotated about an axis extending substantially parallel to the course of said reciprocatory movements, and by which the means for holding the lapping elements may be selectively adjusted to expand or contract the lapping elements during any portion of the rotative or reciprocatory movements of the lapping elements.

A still further object of the invention is to provide a lapping apparatus of this character by which the machine formed grooves and ridges of the surface operated upon can be removed without producing lapping formed surface scratches.

Other objects and advantages of the invention will be more apparent from the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a fragmentary side elevational view of a lapping machine embodying the invention, portions of the structure being broken away and illustrated in section to show the details thereof.

Fig. 2 is a fragmentary vertical sectional view of the rotative and reciprocatory lapping tool adjusting and operating structure of the lapping apparatus shown ln Fig. 1, portions of said structure being illustrated as broken and arranged in side by side adjacency rather than in alignment as in the actual apparatus.

Fi 3 is a horizontal sectional view taken on line 3-4 of Fig. 2.

In the form of the invention illustrated in the drawing, the improved lapping apparatus comprises a base structure, generally designated by 5 the numeral 5, having horizontal and vertical portions 6 and 1 respectively. The horizontal portion 6 has on its upper face a pair of parallel guideways 8 for conveniently guiding the work into lapping receiving relationship with the lapping apparatus, as will presently be more apparent.

The work, generally designated by the reference character 9, is illustrated as comprising a motor block having vertical cylinders to be 16 lapped, but surfaces of other devices may be conveniently lapped without departing from the scope of the invention. A work carrier member I0 is adapted to support the work 9 on the guicleways 8, and includes a pair of lower recesses II which register with the guideways 8. The carrier It] further includes a plurality of locating pins I2 adapted to register with certain portions of the lower face of the work 9, and side arms I3 which centrally position and maintain the work 25 on the guideways 8.

A vertically reciprocable carriage I4 is slidably mounted on the vertical portion 1 of the base structure 5, the carriage having a web portion I5 guidable vertically within a channel 30 forming member I6 detachably secured by bolts Ii to the portion 1. The carriage I4 further comprises an extension member i8, which extends through a vertical elongated slot I9 in the portion 1 and which is adapted to be adjustably 35 positioned by a piston (not shown) operating within a fluid pressure cylinder 20 supported by the portion 1. One extremity of a piston rod 2! is fixed to the piston in the cylinder 20 and its other extremity is detachably secured to the ex tension member I8 by a bolt 22. The interior of the cylinder 20 is communicatively connected with a source of fluid pressure, preferably air pressure, by conduits 23 and 24 which, under the control of suitable automatic or manual valve 45 mechanism (not shown) applies fluid under pres. sure to either end of the cylinder. 20 so as to adjustably or operatively move the tool carriage i4 vertically.

A split casing 25 is detachably secured to the 50 carriage I4 by bolts 29. This casing houses a suitable motor (not shown) for rotating a vertically and reciprocably carried lapping tool, generally designated by the numeral 30, which is carried by a tool holding and operating structure'30'. The-lapping tool operating structure includes a tubular shank portion 3|, having a threaded end and enlarged portions 3| and 3| respectively, and is rotatably and axially reciprocably mounted on the casing 25. A gear 33 (best shown in Figs. 1 and 2) is non-rotatably keyed to the section 3| of the shank 3| at 32', there being provided in the shaft section 3| an elongated keyway 32 for accommodating reciprocatory movement of the shaft relative to the gear 33. A pair of thrust ball bearings 34 and 35 surround and rotatably support the shaft portion 3| and they are disposed between the opposite sides of the gear 33 and thrust bearing collars 31 and 38 mounted in apertures in the portion 21 of the casing 25. The members 31 and 38 together with the bearings 34 and 35 prevent the gear 33 from moving axially relative to the casing 25. A drive shaft 39 is journalled by a bearing block 40 detachably secured to the portion 26 by bolts 4|, and has keyed thereto at 42 a worm gear 43 which is in mesh with the gear 33. The shaft 39 receives its drive from the aforesaid motor housed within the casing 25, and is adapted to be driven while the tubular shaft portion 3| is reciprocated relative to the carriage M by structure hereinafter set forth.

The enlarged portion 3| of the tubular shaft 3| comprises recessed and threaded counterbore portions 44 and 45 respectively and has formed thereon a socket recess 46 in which is received a ball portion 41 of a tubular link member 48, the ball portion 41 being pivotally connected to the portion 3|. A washer 58 is received within the recess 44 on the outer side of the ball portion 41 and is detachably secured therein by a threaded member 5| which threadedly engages the portion 45.

Formed on the tubular member 48, as illustrated in Fig. 2, is a threaded aperture 52 which receives a pair of hemisphere shaped members 53 having apertures 54 aligned with the aperture 52 through which b0lts'55 are threadly engageable with the member 48.

A tubular lapping element holder 56 has a substantially spherical socket portion 51 and recesses 58 to receive the members 53 and 48, and the heads of the bolts respectively. A recessed threaded portion 59 of the holder 56 in axial alignment with and of substantially the same diameter as the recesses 58 admit the members 53, and bolts 55, the recesses 58 preventing rotation of the tubular member 48 relative to the holder 56, and permitting a slight amount of pivotal movement of the member 48 and holder 56 for the centering action of the holder when the work 9 is in lapping receiving relation, as will hereinafter be more apparent. The holder 56 also has an externally threaded portion 6|], an enlarged bore portion 6|, a pair of diametrically opposite vertically extending slots 62, lapping element receiving vertically extending slots 63, and a lower bore portion 64.

A washer is received within the recess portion 6|) against the upper outer portion of the members 53, and a threaded annular'plug 66 is threaded in the holder 56 for retaining the latter washer in place. Slidably supported within the shaft 3| and the tubular member 48 is a piston rod 61 which is adapted under conditions as will soon be apparent to control the expansion of lapping elements toward and contraction away from the surface of the work 9 to be lapped.

Within the bore portion 6| is an annular block 68 having a sliding fit within the bore. The

block 68 comprises threaded apertures 68 aligned with the pair of slots 62, and a pair of centrally aligned apertures 10 and II, the aperture 10 being of larger diameter than the rod 61 and receiving the end portion of the rod 61 which is pivotally connected by a pin 12 to the block 68. The aperture H is of substantially the same diameter as a rod 13 fitted therein and extending axially of the holder 56. The rod 13 is secured to the block 68 by a pin 14, so as to be guidably supported thereby for true central vertical reciprocatory movement. Slight pivotal movement of the end of the rod 61 about the pin 12 is permitted by the large aperture 10 for allowing self-centering action of rod 61. The member 13 has a lower flange portion 15 and is adapted to serve as a mandrel for the lapping tool 38. A pair of pins 16 are threaded in the apertures 69, and they protrude through the vertical guiding slots 62, threaded rings 11 being in adjustable threaded engagement with the threaded portion 68 to limit the upward movement of the rod 61, extension 13, and the block 68.

Fixed to the lower end portion of the rod section 13 is a lapping element positioning member 8| comprising a cylinder slidably fitted within the bore 6| of the tool 56 and seated upon the flange 15. The upper end portion of the cylinder 8| is attached to the rod section 13 by a pin 82. The peripheral portions of this'cylinder are provided with arcuately spaced tapering recesses 80', having inner surfaces 80 inclined with respect to the axis of the rod section 13, into which extend lapping element supports 18. Each support 18 has a lapping stone or other lapping element 19 comprising suitable lapping material, mounted on its outer side and is provided with an inclined opposite side portion which conforms with and is seated upon the inclined surface 80 of the corresponding recess 80' in which it is disposed. The recesses 80' register with the slots 63 of the tubular portion of tool and the supports 18 have portions radially shiftably mounted in these slots with the extremities of the supports guided by the end walls of the slots. The lapping elements which extend through the slots 63 may be variably extended beyond the outer periphery of the tubular portion of the tool by axially upward movement of the cylinder 8|, these lapping elements and their supports being normally yieldably urged inwardly by spring members 84 secured to the tool by screws 85.

The upper end portion of the rod 61 is received within a lower recess of a tubular member 86 of H-shaped cross section having an internal partition which separates its interior into upper and lower recesses respectively. The reduced end portion 9| of a piston rod 81 which imparts vertical movement to the rod 61 is accommodated in the upper recess of this tubular member. The tubular member 86 is received within a sleeve 88 having an inwardly extending flange 89 at its upper end. A pin 90 extending through registering apertures in the member 86, sleeve 88 and rod 61 serves to attach these parts together. Mounted on the reduced end portion 9| of the piston rod 81 is a rolling contact thrust bearing unit 92 which includes a, series of ball bearings interposed. between upper and lower vertically aligned race members which are disposedwithin the sleeve 88 and freely rotatable relative to the latter as well as to the reduced end portion 8| of the rod 81. These ball races are held between a shoulder located at the upper end of the rethereby accurately predetermining the finished duced section 9| and a. washer which is secured to the latter by nuts 93. The ball races extend radially beyond the shoulder of the piston rod 81 and the upper extremity of the top race is engaged by the radial flange 89 of the sleeve 88v as illustrated in Fig. 2. With this construction the piston rod 81 may be relied upon to shift the rod 61 axially of the tube 3I while the latter is rotating and without requiring the piston rod 81 to rotate. Relative rotation between the piston rod 81 and the actuating rod 81 is accommodated by the bearing 9I which coacts with the sleeve 88 and its flange 89 to apply an upwardly directed force on the rod 81, and with the tubular member 88 to apply a downwardly directed force thereon. a

A ball bearing 95 has one of its race members supported by the rod threaded portion 3| and detachably secured thereto by a nut 98. The other race member of the bearing 95 supports an annular member 91 which has an annular groove 98 within which the outer race of the bearing 95 fits.

The annular member 91 is detachably secured by bolts 99 to a pressure cylinder carrying member I88. The member I88 comprises a pressure cylinder portion WI and a partially threaded counterbore portion I82. Within the cylinder IN is a piston I83 which is secured to the upper end of the rod extension 81 and which is adapted to be moved vertically by the admittance of fluid pressure, preferably air pressure, through conduits I84 and I85 communicating with the cylinder I8I above and below the piston I83 respectively. A flanged tubular gland part I86 is received by the portion I8I of the member I88, and provided with annular Sealing ring members I81 and I88 through which the piston rod 81 extends. An annular washer I89 is arranged Within the counterbore portion I82 to hold the sealing members I81 and I88 in leak-proof engagement with the gland part I86; The washer I89 is held in place by an externally threaded sleeve II8 surrounding the nut 96 and threaded in the countcrbore I82.

When rotation is imparted by the shaft 39 to the lapping elements 19 through the shaft 3I the piston I 83 and rod 81 do not rotate for relative rotation between the piston rod 81 and the operating rod 61 is accommodated by the bearing 92 and the loosely fitting members 86 and 88 and the piston is restrained from rotating by engagement of the piston rings of the piston I83 with the cylinder I8I. When the piston I83 is forced downwardly by fluid pressure admitted through. the upper conduit I84 the rod portions 3I and 13 are simultaneously moved until the pins 16 contact the lower extremities of the slots 62 at which time the lowered lapping element positioning member 8| allows the springs 84 to contract the members 18 and 19.

As fluid pressure is admitted through the lower conduit I85 and the fluid pressure above the piston is exhausted through the upper conduit I84, the piston and the rod 61 are raised until the pins 16 strike the adjustable rings 11 during which time the member 8| forces the elements 19 outwardly by reason of its inclined surface. This controllable expansion and contraction of the lapping elements 19 permits removal and insertion of the lapping tool into the cylinder of the work 9 and the adjustable ring 11 facilitates selective predetermining of the extent to which the lapping elements are expanded,

diameter of the work operated upon.

Rotative movement is imparted to the lapping tool, independently of the driving gear 33 and the adjustable movement of the piston within the cylinder 28, by a suitable power source such as the motor III detachably secured by bolts II2 to the carriage I4. The motor has a drive shaft II3 which is keyed at II4 to an eccentric member II5 supporting a ball bearing inner race member H6 and ball bearings II1 which are interposed between the race member and a split outer race member II 8. The outer member II9 comprises an extension arm portion II9 and a cap portion I28 detachably secured together by bolts I2I, the arm portion II9 being pivotally connected at I22 to the member I88.

During operation of the apparatus, the motor III drivingiy reciprocates the lapping tool, preferably at a rate approaching a vibratory order while the tool is rotated by the gear 33 about an axis extending in the general direction of the reciprocatory movement of the tool. The lapping tool may be raised and lowered to bring it out of and into lapping relationship with the work during such reciprocatory and rotative movements or the latter may be discontinued while the tool is being moved toward and away from the work. Movement of the tool into and out of lapping relationship with respect to the work may be accomplished by shifting of the carriage I4 by the action of the piston and cylinder 28 which may be supplied withjfiuid pressure medium through the conduits 23 and 24 under manual or automatic control. When it is desired to subject the lapping tool to a stage of reciprocation in addition to that produced by the motor III and while the tool is rotating, the piston and cylinder 28 may be relied upon to reciprocate the carriage I4 and the lapping tool in unison throughout a long stroke and at a slower rate than that of the reciprocatory movement produced by the motor III. This may be accomplished by suitably alternately admitting fluid medium to the respectively opposite ends of the cylinder 28 through the conduits 23 and 24, and alternately exhausting fluid medium therefrom.

With reference to the operation of this embodiment of the invention, when it is desired to remove the work from lapping receiving relationship with the lapping tool, the prime movers 43 and III are preferably shut off. Fluid pressure is then admitted by any suitable automatic or manual means through the conduit I84 to cause the lapping elements to be contracted, and fluid pressure, preferably air pressure, is exhausted from the upper side of the piston within the cylinder 28 and fluid pressure admitted through the conduit 24 to move the carriage I4 upwardly for carrying the lapping elements upwardly in their contracted condition without putting any surface marks on the work. When the tool holder 15 is in its lower position and the carriage I4 is in its upper position, the lapping tionshipwith the work at a predetermined lapping pressure. The prime movers 43 and III are then started to respectively rotate and to oscillate through the eccentric I IS in short strokes the lapping tool 30, during which movement the piston I03 and the rod extension I01 do not rotate. If desired for purposes of production, the lapping elements can be contracted and the tool removed from the work and inserted into a bore of another piece of work and then expanded without discontinuing the rotation and reciprocation of the tool.

While the prime movers 43 and III are in operation, it is desirable to control the carriage M by imparting comparatively long vertical reciprocatory travel to the carriage to cause the lapping tool 30 to also reciprocate with the carriage while maintaining the lapping elements IS in lapping contact with the work 9. This reciprocatory movement of the carriage I4 is preferably controlled by admitting fluid pressure alternatively to opposite ends of the cylinder 20 from the conduit 22 and the conduit 23 by any suitable automatic or manually controlled valve mechanism. The lapping elements 19 will thereby be simultaneously rotated and also reciprocated in short and long strokes during the lapping operation, resulting in a very efficient lapping apparatus.

Various modiflcations and changes may be effected in the illustrated applications without departing from the spirit of the invention or from the scope of the appended claims.

What we claim is:

1. Lapping apparatus including a support; a tool operating shank rotatively and reciprocatively mounted on said support and adapted to be drivingly rotated and reciprocated relative to said support during operation of said apparatus; a lapping tool head attached to said shank having a plurality of expansibly and contractably mounted lapping elements and including means for variably positioning said lapping elements; and mechanism for controlling said lapping ele ment positioning means including a section carried by said shank and tool head and rotatable therewith, a section carried by said support, and a coupling between said sections so constructed and arranged as to accommodate substantially free rotation of said shank and tool head carried section with respect to said support and said support carried section during operation of said apparatus; and means for drivingly simultaneously reciprocating said shank and said tool head and rotating the same relative to said support.

move the tool holder I5 upwardly to expand the lapping elements into lapping receiving rela-,

2. Lapping apparatusincluding a support having a Journal bearing therein; a tubular tool operating shank rotatively and reciprocably shiftably mounted in said journal bearing for rotative and reciprocative movement relative thereto'and adapted to be drivingly rotated during operation of said apparatus; mechanism for drivingly reciprocating and rotating said shank a lapping tool attached to said tubular shank having a plurality of expansibly and contractably mounted lapping elements and including means for variably positioning said lapping elements; and mechanism for controlling said lapping element positioning means including a rod axially shiftably mounted within said tubular shank, and an actuating member movably carried by said reciprocating mechanism, and a rolling contact thrust bearing coupling between said actuating member and said rod so constructed and arranged as to accommodate substantially free rotation of said rod with respect to said actuating member during operation of said apparatus.

3. Apparatus including a frame structure; a support reciprocably mounted on said structure; a tool operating shank rotatively and reciprocatively mounted on said support and adapted to be drivingly rotated during operation of said apparatus; a lapping tool attached to said shank having a plurality of expansibly and contractably mounted lapping elements and including means for variably positioning said lapping elements; means including a driving member carried by said support for reciprocating said tool relative thereto at a rate of substantially vibratory order; means for reciprocating said support relative to said frame structure at a lower rate: mechanism for controlling said lapping element positioning means including a connecting member having one end operatively connected therewith andcarried by said shank and rotatable with the latter, an actuating member carried by said tool reciprocating means, and a coupling between said actuating member and the other end of said connecting member so constructed and arranged as to accommodate substantially free a rotation of said connecting member with respect to said actuating member during operation of said apparatus; and means for drivingly simultaneously reciprocating said tool relative to said support at said vibratory order and said support relative to said frame structure at said lower rate during rotation of said tool.

DAVID A. WALLACE. EDWARD C. LEE. 

